1. Field of the Invention
The present invention relates to a pattern writing apparatus for recording an image on a photosensitive material.
2. Description of the Background Art
Conventionally well known is a technique for irradiating a photoresist film formed on a semiconductor substrate, a printed board, a glass substrate for photomask or the like (hereinafter, referred to as “substrate”) with a light beam modulated by a spatial light modulator such as a DMD (digital micromirror device) or a liquid crystal shutter, to write a fine pattern (i.e., record an image).
Japanese Patent Application Laid Open Gazette No. 62-21220 discloses a method to expose a fine pattern, by irradiating a photosensitive material with a light beam spatially modulated by a group of micromirrors of a DMD while feeding the photosensitive material at only a set distance and controlling a signal for the DMD.
Though a technique for pattern writing, which uses only one spatial light modulator, is conventionally proposed, it takes a long time to write a pattern which widely extends when only one spatial light modulator is used. For high-speed writing, use of a plurality of spatial light modulators is considered, but in a case of writing a fine pattern, if a plurality of spatial light modulators are simply arranged for use, it is not easy to join images written on the photosensitive material by the spatial light modulators.
In other words, recently, with refinement of patterns to be formed, a microscopic deformation of a substrate, a microscopic deviation of a substrate holding position or the like greatly affects the precision of written pattern, and due to such an ill effect, it has been conventionally impossible to write a fine pattern at high speed.